The present invention relates to a magnetic tape cassette and, more specifically, to a video magnetic tape cassette in which a reel retaining plate depresses the tops of hubs of a pair of tape reels to urge the tape reels in an axial direction. The depression force of the reel plate helps ensure that a tape is transported from reel to reel at a constant speed, and it is precisely positioned in the vicinity of read, write and erase heads in a recorder as the tape is transported. In addition, the reel retaining plate provides centers of rotation for the tape reels.
Heretofore, in a video tape cassette, a reel retaining plate suitably depresses central portions of the hubs of the reels in order to allow the reels to rotate smoothly so that the tape is transported in a uniform manner, thus improving the picture recording and reproducing quality of the cassette. The reel retaining plate is made from an elastic material and is mounted on an upper cassette half. The plate or its contact portions are bent in the direction of depression and are brought into contact with the tops of the hubs. The end portions of the reel retaining plate are usually bent and lightly depress the tops of the hubs.
FIG. 1 shows a conventional reel retaining plate 3, the plate 3 being supported like a cantilever from the upper cassette half. According to this construction, the plate must be rigidly secured to the upper cassette half, and the plate is therefore secured at the two points 7 by pressurizing, heating, adhering or ultrasonic welding. If the plate 3 is not positively secured at the two points 7, the plate 3 will play. As a result, the depression force of the end portions 11 of the plate 3 on the hubs becomes irregular. This has an adverse effect on the positioning and running speed of the tape as it is transported from reel to reel, and, accordingly, picture recording and reproducing characteristics are adversely affected. Furthermore, the tape may be wound unsatisfactorily. In small video tape cassettes, the space for mounting the reel retaining plate is very small, and, therefore, the above-described problem becomes more serious, and the reel retaining plate must be mounted more carefully.